JPH11310678A - Low swelling rubber composition and molded article obtained from the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low swelling rubber composition having excellent fuel oil resistance, fuel oil permeation resistance and chemical resistance, to provide a molded product obtained from the same, to provided a rubber laminated using the same, and to provide a rubber article comprising the same. SOLUTION: This low swelling rubber composition comprises 0.1-15 pts.wt. of a peroxide cross-linking agent and 100 pts.wt. of a composition comprising 5-95 wt.% of a peroxide cross-linkable fluororubber having a vinylidene fluoride copolymerization ratio of 45-88 mol.% and a number-average mol.wt. of 5,000-200,000 and 95-5 wt.% of an acrylic rubber which is copolymerized with 0.1-1.5 wt.% of a polyfunctional monomer and >=20 wt.% of (meth)acrylic acid alkoxy-substituted alkyl ester and/or >=4 wt.% of acrylonitrile. The polyfunctional monomer having a functional group capable of being copolymerized with the (meth)acrylate easter and further having a functional group capable of being cocross-linked with the fluororubber with the oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a low-swelling rubber composition and a molded product obtained therefrom.

[0002]

2. Description of the Related Art Fluororubber is excellent in fuel oil resistance, chemical resistance and the like, and is useful in industrial materials, automotive materials, and other fields. However, economical efficiency cannot be ignored for general-purpose use in these fields, and it is not possible to expect a dramatic increase in usage while having excellent performance. Acrylic rubber is widely used in automobiles under the environment where it comes into contact with engine oil and transmission oil because of its excellent oil resistance. Not used. In addition to fluororubbers, nitrile rubbers or their hydrides and hydrin rubbers have relatively good fuel oil resistance and are often used as materials used in environments that come into contact with fuel oil.

[0003]

However, in recent years, regulations regarding the amount of fuel released to the atmosphere have been started in automobiles due to environmental problems. Nitrile rubber or its hydride or hydrin rubber has low resistance to fuel oil and oil. Fuel permeability is becoming insufficient. In order to solve such problems, a method of laminating a rubber such as a nitrile rubber or a hydride thereof, or a hydrin rubber and a fluorine rubber and forming a hose therewith has been studied and implemented. Due to poor affinity with rubber and different vulcanization methods, there was a processing problem that the adhesion between the layers when laminated was low and the film was easily peeled off. Further, in consideration of economy, it is difficult to sufficiently improve the fuel oil resistance and the fuel permeation resistance as a hose because the amount of fluoro rubber used is limited. The object of the present invention is to provide fuel oil resistance, fuel permeability resistance,
An object of the present invention is to provide a low-swelling rubber composition having excellent chemical resistance, a molded product obtained therefrom, a rubber laminate using the same, and a rubber product comprising the same.

[0004]

The present invention relates to a low-swelling rubber composition described below and a molded product obtained therefrom. Low swelling rubber composition: copolymerization ratio of vinylidene fluoride is 45 to 88 mol%, and number average molecular weight is 5,000 to 2
00,000 peroxide crosslinkable fluoro rubber 5
Polyfunctional monomers having a functional group enabling peroxide co-crosslinking with fluororubber and a functional group enabling copolymerization with (meth) acrylic acid ester, respectively. 5% by weight copolymerized, 20% by weight or more of (meth) acrylic acid alkoxy-substituted alkyl ester and / or 4% by weight of acrylonitrile
A low swelling rubber composition in which 0.1 to 15 parts by weight of a peroxide crosslinking agent is blended with 100 parts by weight of a composition comprising 95 to 5% by weight of an acrylic rubber copolymerized as described above (referred to as "formulation (A)"). . Here, the (meth) acrylate includes alkyl (meth) acrylate and alkoxy-substituted alkyl (meth) acrylate.

[0005]

DETAILED DESCRIPTION OF THE INVENTION In the low swellable rubber composition of the present invention, the peroxide-crosslinkable fluororubber is, for example, a vinylidene fluoride / hexafluoropropylene system.
Vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene system, vinylidene fluoride /
Vinylidene fluoride copolymers such as chlorotrifluoroethylene, tetrafluoroethylene / propylene, hexafluoropropylene / ethylene, and fluoro (alkyl vinyl ether) / olefins (for example, vinylidene fluoride / tetrafluoroethylene /
Perfluoroalkyl vinyl ether), and among these, vinylidene fluoride / hexafluoropropylene-based and vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene-based elastomers are preferable. The fluoro (alkyl vinyl ether) may contain a plurality of ether bonds. Further, the number average molecular weight is 5,000 to 200,000, preferably 50,000 to
170,000 is good. If the molecular weight is 200,000 or more, sufficient processability cannot be obtained, and if it is less than 5,000, the properties after vulcanization are not sufficient. The workability here means polymer viscosity at high temperature, vulcanization characteristics, roll workability, and the like. The vinylidene fluoride copolymerization ratio of the fluororubber is preferably 45 to 88 mol%, more preferably 55 to 85 mol%.

[0006] If the vinylidene fluoride copolymerization ratio is less than 45 mol%, the compatibility with the acrylic rubber is inferior, and it is difficult to enhance the dispersibility of the polymer, so that sufficient mechanical properties cannot be obtained. On the other hand, if it exceeds 88 mol%, the compression set becomes low. The iodine-containing fluororubber will be described below as an example of the fluororubber of the present invention. Preferred examples of the iodine-containing fluororubber include a radical generator and a general formula: R
Ix (wherein, R is a saturated or unsaturated fluorocarbon group having 1 to 16 carbon atoms, a chlorofluorohydrocarbon group, or a hydrocarbon group having 1 to 3 carbon atoms, and x is the number of bonds of R In the presence of an iodine compound represented by the formula (1), in addition to vinylidene fluoride (VdF), a fluorine-containing ethylenically unsaturated compound having 2 to 8 carbon atoms (and optionally carbon atoms). At least one monomer composed of 2 to 4 fluorine-free ethylenically unsaturated compounds)
An easily curable fluorine-containing polymer obtained by polymerizing a seed (see JP-A-53-125491) can be exemplified. As a preferred iodine-containing fluororubber, vinylidene fluoride (VdF) units are 45 to 88 mol%,
It is preferably 55-85 mol%, and tetrafluoroethylene (TFE) units are 0-45 mol%, preferably 0-30 mol%.
Mol%, hexafluoropropylene (HFP) unit is 1
Copolymers containing 0 to 40 mol%, preferably 10 to 25 mol%, can be mentioned.

In the low swelling rubber composition of the present invention, the acrylic rubber is an alkyl (meth) acrylate, a polyfunctional monomer, an alkoxy-substituted alkyl (meth) acrylate, acrylonitrile, an ethylenically unsaturated monomer Can be appropriately combined and copolymerized by a known polymerization method. Examples of the alkyl (meth) acrylate include compounds represented by CH ₂ ＣC (R ¹ ) COOR ² (R ¹ is methyl or ethyl, and R ² is an alkyl group having 1 to 18 carbon atoms). Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, Isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-methylpentyl (meth) acrylate, n-octyl (meth) acrylate, 2-
Ethylhexyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, n-octadecyl (meth) acrylate and the like are preferable, and methyl acrylate, ethyl acrylate, n-propyl acrylate, and n-butyl are preferable. Acrylate, particularly preferably ethyl acrylate, n-
Butyl acrylate.

The polyfunctional monomer is a monomer having two or more double bonds in the molecule, and (a) a functional group capable of co-crosslinking a peroxide with a fluororubber; and (b) a (meth) acrylate ester. Each having a functional group that enables copolymerization with Specific examples include, for example, ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, allyl (meth) acrylate , Divinylbenzene, triallyl cyanurate, triallyl isocyanurate and the like.
If a functional group or a functional group is used, it tends to be difficult to control the ratio of partial cross-linking during polymerization. Monomers containing only one double bond in the molecule do not have a cross-linking group remaining in the acrylic rubber, so that co-crosslinking with a fluororubber is difficult. Further, among the bifunctional ones, those having different reactivity of both double bond portions are more preferable, and allyl (meth) acrylate is more preferable in the sense that a double bond portion on one side remains as a cross-linking group in the acrylic rubber. In addition, dihydrodicyclopentenyl acrylate, ethylidene norbornene, and the like having different reactivity of both double bond moieties are used. No, it must be used in combination with allyl (meth) acrylate.

The amount of the polyfunctional monomer used is preferably from 0.1 to 1.5% by weight, more preferably from 0.3 to 0.7% by weight, based on the total amount of the (meth) acrylate, acrylonitrile and polyfunctional monomer. If the amount of the polyfunctional monomer is small, the crosslinking of the acrylic rubber is insufficient and vulcanization molding is difficult, and heat resistance, mechanical properties and the like are inferior. In addition, if the amount of polyfunctional monomer is large, partial cross-linking during polymerization increases and the processability is impaired. In addition, the cross-linking density after vulcanization becomes too high, resulting in loss of flexibility and reduction in elongation. Can not.

Examples of the (meth) acrylic acid alkoxy-substituted alkyl ester include CH ₂ ＣC (R ¹ ) COO-AOR ³ (A is an alkylene group having 1 to 12 carbon atoms, and R ¹ is the same as described above. R ³ represents an alkyl group having 1 to 12 carbon atoms). Specific examples thereof include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, and 2-methoxyethyl (meth) acrylate. (N-propoxy) ethyl (meth) acrylate, 2- (n-butoxy) ethyl (meth) acrylate, 3-methoxypropyl (meth)
Acrylate, 3-ethoxypropyl (meth) acrylate, 2- (n-propoxy) propyl (meth) acrylate, 2- (n-butoxy) propyl (meth) acrylate, and the like, preferably 2-methoxyethyl acrylate, -Ethoxyethyl acrylate, particularly preferably 2-methoxyethyl acrylate.

The amount of the alkoxy-substituted alkyl (meth) acrylate is preferably 20 to 99.9% by weight. If the amount of the (meth) acrylic acid alkoxy-substituted alkyl ester is less than 20% by weight, the fuel oil resistance and the fuel permeation resistance are inferior when the blend ratio of the fluoro rubber and the acrylic rubber is fixed for reasons such as economy. The amount of acrylonitrile used is preferably 4 to 15% by weight. If the amount of acrylonitrile used is less than 4% by weight, the fuel oil resistance and fuel permeation resistance are inferior when the blend ratio of fluororubber and acrylic rubber is fixed for reasons such as economy. If it is 15% by weight or more, the low-temperature property is inferior. Further, when the amount of the alkoxy-substituted alkyl (meth) acrylate used is 20% by weight or more and the amount of the acrylonitrile is 4% by weight or more, the fuel oil resistance and the fuel permeation resistance are further improved.
R ² and R ³ preferably have 1 to 4 carbon atoms. The higher the carbon number and the higher the copolymerization ratio, the better the low-temperature property, but the poorer the fuel oil resistance and the compatibility with the fluororubber.

For the purpose of modifying the polymer, if necessary, a part of the (meth) acrylate monomer may be replaced with an ethylenically unsaturated monomer such as styrene, vinyl acetate, ethylene, vinyl chloride or the like to carry out polymerization. The amount is preferably not more than 20% by weight of the (meth) acrylate monomer. In the rubber compound (A) of the present invention, the ratio of fluororubber to acrylic rubber is such that the ratio of fluororubber / acryl rubber is 5 to 95/95 to 5, preferably 10
~ 90 / 90-10, more preferably 25-75 / 75
~ 25. If the amount of the fluoro rubber is less than this, the effect of improving the fuel oil resistance becomes insufficient and the processability such as flowability deteriorates. It is not economically desirable to use more fluorine rubber than this.

As the peroxide crosslinking agent used in the low swelling rubber composition of the present invention, those which easily generate peroxy radicals easily in the presence of heat or an oxidation-reduction system, for example, 1,1- Bis (t-butylperoxy) -3,5,5-trimethylcyclohexane, 2,5-
Dimethylhexane-2,5-dihydroxy peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α, α′-bis (t
-Butylperoxy) -p-diisopropylbenzene,
2,5-dimethyl-2,5-di (t-butylperoxy)
Hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, benzoyl peroxide, t
-Butylperoxybenzene, 2,5-dimethyl-2,5
-Di (benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate and the like. Especially preferred are compounds of the dialkyl type. In general, the type and amount used are selected from the amount of active -OO-, the decomposition temperature, and the like. The amount used is usually 0.1 to 100 parts by weight of the polymer (total of acrylic rubber and fluoro rubber).
The amount is 15 parts by weight, preferably 0.3 to 5 parts by weight.

[0014] If necessary, a crosslinking aid may be used in combination. This crosslinking aid is effective in principle as long as it has a reaction activity for peroxy radicals and polymer radicals, and the type is not particularly limited. Preferred are triallyl cyanurate, triallyl isocyanurate, triallyl formal, triallyl trimellitate, dipropargyl terephthalate, diallyl phthalate, tetraallyl terephthalamide,
Triallyl phosphate, bismaleimide and the like. It is not always necessary to use a crosslinking aid, but if used, 0.1 to 10 parts by weight per 100 parts by weight of the polymer.
The weight ratio is preferably from 0.3 to 5 parts by weight. Further, a cross-linking agent, a cross-linking aid, and other fillers to be mixed with the mating material in the case of laminating may be mixed as necessary. In the low swelling rubber composition of the present invention, a processing aid, an antioxidant, an antioxidant, an antiozonant, an ultraviolet absorber and the like can be further added as required.

Examples of the filler include metal oxides such as magnesium oxide, calcium oxide, titanium oxide, silicon oxide, and aluminum oxide; metal hydroxides such as magnesium hydroxide, aluminum hydroxide, and calcium hydroxide; magnesium carbonate; and aluminum carbonate. Carbonates such as calcium carbonate and barium carbonate, silicates such as magnesium silicate, calcium silicate, sodium silicate and aluminum silicate, sulfates such as aluminum sulfate, calcium sulfate and barium sulfate,
Synthetic hydrotalcite, molybdenum disulfide, iron sulfide,
Examples include metal sulfides such as copper sulfide, diatomaceous earth, asbestos, lithopone (zinc sulfide / barium sulfide), graphite, carbon black, carbon fluoride, calcium fluoride, coke, and the like.

Examples of the processing aid include higher fatty acids such as stearic acid, oleic acid, palmitic acid and lauric acid, higher fatty acid salts such as sodium stearate and zinc stearate, higher fatty acid amides such as stearamide and oleamide, and the like. Higher fatty acid esters such as ethyl oleate; higher aliphatic amines such as stearylamine and oleylamine; petroleum waxes such as carnauba wax and ceresin wax; polyglycols such as ethylene glycol, glycerin and diethylene glycol; and aliphatic carbons such as petrolatum and paraffin. Hydrogen, silicone oil, silicone polymer, low molecular weight polyethylene, phthalates, phosphates, rosin, (halogenated) dialkylamine, (halogenated) dialkylsulfone,
Surfactants and the like.

Antioxidants, anti-aging agents and antiozonants include phenols such as 2,5-di-t-amylhydroquinoline and amines such as 2,2,4-trimethyl-1,2-dihydroquinoline. And compounds such as aromatic ketones and aromatic secondary amines such as 4,4′-bis (α, α′-dimethylbenzyl) diphenylamine. As an ultraviolet absorber, benzophenones such as 2,4-dihydroxybenzophenone, bis (2,2,6,6-
Examples thereof include compounds such as amines such as tetramethyl-4-piperidyl) sebacate and benzotriazoles such as 2- (2′-hydroxy-5′-methylphenyl) benzotriazole.

In the present invention, a rubber layer (1) containing the low swelling rubber composition and a rubber layer (2) containing another rubber compound are vulcanized and bonded to form a rubber laminate. You can also get. The rubber layer (2) in the present invention is not particularly limited as long as it is a rubber capable of being sufficiently vulcanized and adhered to a low swelling rubber composition, but is not particularly limited to nitrile rubber or a hydride thereof, styrene-butadiene rubber. Rubber, chloroprene rubber, ethylene-propylene-termonomer copolymer rubber, chlorinated polyethylene, chlorosulfonated polyethylene, silicone rubber, butyl rubber, hydrin rubber, fluorine rubber, acrylic rubber, ethylene-vinyl acetate copolymer Is mentioned. Of these, fluorine-based rubber, acrylic rubber, hydrin-based rubber, nitrile-based rubber and hydrides thereof are particularly preferred.

The fluorine-based rubber referred to herein is, for example, vinylidene fluoride / hexafluoropropylene, vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene, vinylidene fluoride / chlorotrifluoroethylene or the like vinylidene fluoride. Copolymers, tetrafluoroethylene / propylene, tetrafluoroethylene / vinylidene fluoride / propylene, hexafluoropropylene / ethylene, fluoro (alkyl vinyl ether) / olefin (eg, vinylidene fluoride / tetrafluoroethylene / perfluoro) Alkyl vinyl ether), among which vinylidene fluoride / hexafluoropropylene, vinylidene fluoride / Tetrafluoroethylene / hexafluoropropylene-based elastomer are preferable. The fluoro (alkyl vinyl ether) may contain a plurality of ether bonds.

The acrylic rubber referred to here includes:
(A) 30 to 99.9% by weight of an alkyl (meth) acrylate and / or an alkoxy-substituted (meth) acrylate alkyl ester compound, (b) a crosslinkable monomer
A multi-component copolymer rubber having a weight composition of 0.1 to 10% by weight and (c) 0 to 70% by weight of another ethylenically unsaturated compound copolymerizable with the above (a) and (b). As the nitrile rubber, α, β-unsaturated nitrile [(d)
Component] 10 to 60% by weight, conjugated diene [Component (e)] 1
A multi-component copolymer rubber having a weight composition of 5 to 90% by weight and 0 to 75% by weight of another ethylenically unsaturated compound copolymerizable with the components (d) and (e).

Examples of the alkyl (meth) acrylate include a compound represented by CH ₂ ＣC (R ¹ ) COOR ² (R ¹ and R ² are the same as above). Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate,
Isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isoamyl (meth) acrylate,
n-hexyl (meth) acrylate, 2-methylpentyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n
-Decyl (meth) acrylate, n-dodecyl (meth)
Acrylate, n-octadecyl (meth) acrylate and the like can be mentioned, preferably methyl acrylate, ethyl acrylate, n-propyl acrylate and n-butyl acrylate, and particularly preferably methyl acrylate and ethyl acrylate.

The above (meth) acrylic acid alkoxy-substituted alkyl ester is, for example, a compound represented by CH ₂ ＣC (R ¹ ) COO-A-OR ³ (A, R ¹ and R ³ are the same as above) Specific examples thereof include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2- (n-propoxy) ethyl (meth) acrylate, and 2- (n-butoxy) ethyl ( (Meth) acrylate, 3-methoxypropyl (meth) acrylate, 3
-Ethoxypropyl (meth) acrylate, 2- (n-
Propoxy) propyl (meth) acrylate, 2- (n
-Butoxy) propyl (meth) acrylate and the like, preferably 2-methoxyethyl acrylate,
-Ethoxyethyl acrylate, particularly preferably 2-methoxyethyl acrylate.

Examples of the crosslinkable monomer include dicyclopentadiene, ethylidene norbornene, vinyl chloroacetate, allyl chloroacetate, 2-chloroethyl vinyl ether, vinyl (meth) acrylate, allyl (meth) acrylate, glycidyl (meth) acrylate, dimethyl Steryl vinyl silane, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, alkyl glycidyl ether, vinyl glycidyl ether, 2-chloroethyl (meth) acrylate, monochlorovinyl acetate, vinyl norbornene, acrylic acid, methacrylic acid , Itaconic acid or the like.

Examples of the ethylenically unsaturated compound include carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, 2-pentenoic acid, maleic acid, fumaric acid and itaconic acid, methyl methacrylate, octyl methacrylate and methyl vinyl ketone. Alkyl vinyl ketones, vinyl and allyl ethers such as vinyl ethyl ether and acryl methyl ether, vinyl aromatic compounds such as styrene, α-methyl styrene, chlorostyrene and vinyl toluene, nitriles such as acrylonitrile and methacrylonitrile, acrylamide and meta Amides such as acrylamide, N-methylol acrylamide and ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl acetate, alkyl fumarate, etc. It is below. Of these, acrylonitrile, ethylene and vinyl acetate are preferred, and acrylonitrile and ethylene are particularly preferred.

Specific examples of the α, β-unsaturated nitrile include acrylonitrile, α-chloroacrylonitrile, α-fluoroacrylonitrile, methacrylonitrile, ethacrylonitrile and the like, and acrylonitrile is preferred. As the conjugated diene, 1,3-butadiene, 2-chloro-1,3-butadiene, 2-methyl-
Examples thereof include 1,3-butadiene, among which 1,3-butadiene is preferable. Further, these rubbers may be blended with a resin such as polyvinyl chloride for improving the economy and the fuel permeation resistance.

As a method for producing the low swelling composition of the present invention, a usual mixing apparatus is used, and a method of mixing fluororubber, acrylic rubber and a compounding agent by an open roll,
Examples thereof include a method using an internal mixer, a method of co-coagulating from emulsion mixing, and the like. Further, these methods may be used in combination. The production of a molded article can be performed by a known method such as a method of heating and compressing with a mold, a method of press-fitting the composition into a heated mold, and a method of extruding and steam-heating with an extruder. Further, secondary vulcanization may be performed by heat-treating the molded product in order to improve the properties.

The rubber laminate can be manufactured by the following method. That is, a low-swelling rubber composition kneaded with a mixer such as a cooling roll, a Banbury mixer, or an intermixer, and another compound obtained in the same manner, are simultaneously extruded in two layers by an extruder, or The outer layer is extruded on the inner layer by the base extruder to form an inner tube rubber layer composed of an inner layer and an outer layer, and the outer tube rubber layer is extruded by an extruder to be integrated, and then vulcanized and bonded. Can be manufactured. The rubber layer (1) composed of the low swelling rubber composition and the rubber layer (2) composed of the other rubber compound may be used as an inner layer or an outer layer of the inner tube rubber layer depending on the use. Can also.

The molded article and the rubber laminate comprising the low swellable rubber composition of the present invention can sufficiently withstand use under severe conditions and have various uses. Hose, packing, diaphragm, tube, lining, O-, etc. that require low swelling such as motion system, valve system, lubrication / cooling system, fuel system, intake / exhaust system, etc.
It has suitable properties as rings, rolls, etc., especially for applications that come into contact with fuel oil, specifically oil seals, diaphragms, valves, fillers (necks) for fuel pumps
Fuel hoses such as hoses, fuel supply hoses, fuel return hoses, vapor (evaporation) hoses, vent (breather) hoses, in-tank hoses for fuel tanks, filler seals, tank packing, in-tank fuel pump mounts, and fuel tubes for fuel tubes O-ring itself, connector O-ring, injector cushion ring for fuel injector, injector seal ring, injector O-ring, pressure regulator diaphragm, check valve, carburetor needle valve core valve, acceleration pump piston packing, flange gasket, It can be optimally used as a control hose, a valve seat for a composite air control device, a diaphragm, and the like.

[0029]

The present invention will be described in detail below with reference to examples and comparative examples. Hereinafter, “parts” means “parts by weight”. a) Polymerization of acrylic rubber In a separable flask equipped with a thermometer, a stirrer, a nitrogen inlet tube and a decompression device, 480 parts of water, 0.24 parts of sodium bicarbonate, 0.48 parts of sodium lauryl sulfate, Nonipol 200 ( 0.448 parts of polyoxyethylene nonylphenyl ether) and 100 parts of the monomer mixture shown in Table 1 were charged, and oxygen in the system was sufficiently removed while repeating degassing and nitrogen substitution.
01 parts, 0.002 parts of sodium formaldehyde sulfoxylate and 0.003 parts of tertiary butyl hydroperoxide.
005 parts was added and the polymerization reaction was started at 50 ° C. After reacting for 6 hours so that the polymerization conversion was in the range of 95 to 99%, the reaction product was salted out, sufficiently washed with water and dried to obtain an acrylic rubber. EA is ethyl acrylate, MEA is 2
-Methoxyethyl acrylate, AN represents acrylonitrile. Allyl methacrylate (hereinafter abbreviated as AMA) is a product of Acryester A manufactured by Mitsubishi Rayon Co., Ltd.
Was used as is. A-3 to A-6 are Examples and A-1.
And A-2 are comparative examples.

[0030]

[Table 1]

B) Polymerization of Fluororubber 1 l of pure water and C ₇ F ₁₅ COONH ₄ as an emulsifier were placed in a stainless steel polymerization tank having an inner volume of 3 liters.
After charging 2 g and thoroughly replacing the inside of the system with nitrogen gas, 8 g
At 0 ° C., an initial monomer mixture of VdF / HFP / TFE was injected such that the internal pressure was 16 kg / cm ² G. Then, 10 ml of a 0.2% by weight aqueous solution of ammonium persulfate was injected to start the reaction. Since the pressure decreases with the progress of the polymerization reaction, when the pressure has decreased to 15 kg / cm ² G, I (CF ₂ ) ₄ I, which is a molecular weight regulator, was injected, and the pressure further decreased to 14 kg / cm ² G. VdF / HFP / TF at the time
The continuous monomer mixture of E was repressurized to 16 kg / cm ² G, and the reaction was continued by repeatedly injecting 10 ml of the above ammonium persulfate aqueous solution with nitrogen gas every 3 hours while repeatedly decreasing and increasing the pressure. Obtained. To this aqueous emulsion, a 5% by weight aqueous solution of potassium alum was added for coagulation, and the coagulated product was washed with water and dried to obtain a rubber copolymer. Table 2 shows the initial monomer mixture, the amount of I (CF ₂ ) ₄ I, the continuous monomer mixture, the reaction time, and the yield. Where 2
F is VdF (vinylidene fluoride), 4F is TFE
(Tetrafluoroethylene) and 6F indicate HFP (hexafluoropropylene).

[0032]

[Table 2]

The number average molecular weight and Mooney viscosity (ML _{1 + 10} , 100 ° C.) of the copolymer were determined by the following methods. <Molecular weight measurement conditions> Gel permeation chromatography: High-speed GPC device HLC-8020 [Tosoh Corporation]
Column: TSK guard column Hhr-H (1) TSK gel -G5000H, -G4000H, -G3
000H, -G2000H (one each) [Tosoh Corporation
Detector: RI detector (differential refractometer) HLC-8020
Data analysis: Super system controller SC-
8020 [manufactured by Tosoh Corporation] Developing solvent: tetrahydrofuran Temperature: 35 ° C Concentration: 0.5% by weight Standard polymer for molecular weight calibration curve: various types of monodisperse polystyrene TSK standard POLYSTYLEN [Mw /
Mn = 1.14 (max)] [manufactured by Tosoh Corporation] The composition of the copolymer was determined by 19F NMR measurement. <Mooney viscosity> The measurement was performed according to JIS K6300.

[0034]

[Table 3]

[0035]

Examples 1 to 14 Fluorine rubber, acrylic rubber and compounding agents were kneaded in the amounts shown in Table 4 with an open roll to obtain a low-swelling composition. These are vulcanized at 160 ° C. for 20 minutes,
Oven vulcanization was performed at 0 ° C. for 4 hours. Seast 116 is MAF type carbon black made by Tokai Carbon, TAI
C is triallyl isocyanurate manufactured by Nippon Kasei, Perhexa 25B is a peroxide manufactured by Nippon Yushi, and Nowguard 445 is an antioxidant manufactured by Uniroyal. The physical properties were measured according to JIS K-6301. The fuel oil resistance was measured using Fuel C (isooctane / toluene =
(50/50 volume ratio) at 40 ° C. for 48 hours, and the volume change rate of the test piece before and after immersion was determined. Fuel permeation resistance is 20 cc in a stainless steel container.
After 14 cc of C was added and a test vulcanized sheet having a thickness of about 0.5 mm was covered thereon, it was fixed and sealed with a stainless steel lid having an opening of 15 cm ² from above. 40 ℃
After one day in a thermostatic chamber adjusted to
(G) was measured, and the weight W after being placed in a thermostat for 2 days.
2 (g) is measured, and the transmission speed is calculated by a formula (W1-W2) ×
Thickness / (opening area × measurement days) was calculated. Table 5 shows the results.

[0036]

[Table 4]

[0037]

[Table 5]

Comparative Examples 1-3 Compositions were prepared in the same manner as in the Examples except that the fluororubber, acrylic rubber and compounding agents were kneaded in the amounts shown in Table 6. The physical properties were measured in the same manner as in the examples.

[0039]

[Table 6]

[0040]

[Table 7]

[0041]

By using the low swelling rubber composition of the present invention, it is possible to provide a molded article having excellent fuel oil resistance, chemical resistance and fuel permeability resistance.

Claims (10)

[Claims] 1. The copolymerization ratio of vinylidene fluoride is 4
5 to 88 mol%, number average molecular weight of 5,000 to 200,0
5 to 95% by weight of a peroxide-crosslinkable fluororubber of No. 00, and a functional group that enables peroxide co-crosslinking with the fluororubber and a functional group that enables copolymerization with a (meth) acrylate. Acrylic rubber 95 to which 0.1 to 1.5% by weight of a polyfunctional monomer is copolymerized, 20% by weight or more of an alkoxy-substituted alkyl (meth) acrylate is copolymerized and / or 4% by weight or more of acrylonitrile is copolymerized. Formulation 10 consisting of 5% by weight
The peroxide crosslinking agent is used in an amount of 0.1 to 1 part by weight based on 0 part by weight.
A low swelling rubber composition mixed with 5 parts by weight. 2. The low swelling rubber composition according to claim 1, further comprising 0.1 to 10 parts by weight of a crosslinking aid based on 100 parts by weight of the polymer.
A low swelling rubber composition blended by weight. 3. The low swelling rubber composition according to claim 1, wherein 25 to 75% by weight of a fluororubber and 75 to 25% by weight of an acrylic rubber are used. 4. The low swelling rubber composition according to claim 1, wherein the fluororubber is an iodine-containing fluororubber. 5. The low swellable rubber composition according to claim 1, wherein the polyfunctional monomer is allyl (meth) acrylate. 6. A rubber molded article obtained by co-crosslinking the low swelling rubber composition according to claim 1 with a peroxide. 7. A rubber product wherein the molded product according to claim 6 is a hose, a packing, a diaphragm, a tube, a lining, an O-ring, or a roll. 8. A rubber laminate in which the rubber layer (1) containing the low swelling rubber composition according to claim 1 and the rubber layer (2) containing another rubber compound are vulcanized and bonded. body. 9. The rubber layer (2) whose nitrile rubber or its hydride, styrene-butadiene rubber, chloroprene rubber, ethylene-propylene-termonomer copolymer rubber, chlorinated polyethylene, chlorosulfonated polyethylene, silicone The rubber laminate according to claim 8, which is a rubber layer containing rubber, butyl rubber, hydrin rubber, fluorine rubber, acrylic rubber, and ethylene-vinyl acetate copolymer. 10. A rubber product, wherein the laminate according to claim 8 is a hose, a packing, a diaphragm, a tube, a lining, an O-ring, or a roll.